Hybrid-electric vehicles (HEVs) and battery electric vehicles (BEVs) may rely on a traction battery to power a traction motor for propulsion, and a power inverter there between to convert direct current (DC) power to alternating current (AC) power. The typical AC traction motor is a three-phase motor powered by three sinusoidal signals each driven with 120 degrees phase separation but other configurations are also possible.
While the use of traction motors in hybrid vehicles can improve fuel economy and emissions performance relative to conventional internal combustion engine vehicles, they may generate unwanted noise. One source of noise springs from the pulse width modulation (PWM) of switched power converters. Although the PWM carrier frequency can be varied such that narrow-band noise is converted to lower magnitude wide-band noise, this may increase the likelihood of resultant electromechanical torques/forces exciting system resonant frequencies, which may lead to momentary increases in acoustic emissions.